1. Field of the Invention
The present invention relates to an interactive projection system and a method for calibrating position of a light point; in particular, to an interactive projection system which can sense the invisible light point and an automatic calibration method for the position of the light point thereof.
2. Description of Related Art
The present projection system develops an interactive projection system, which usually includes a projection device, an image sensor, and a pointer. The pointer has an infrared light source and can emit invisible infrared light. The image sensor is such as a CMOS image sensor (CIS) and capable of sensing the infrared light from the pointer.
When the projection device projects an image onto a screen according to data that a computer outputs, the pointer can be used for emitting the infrared light to the screen, thereby forming an invisible light point on the screen. Meanwhile, the image sensor senses and tracks the light point so that the image projected from the projection device can show a position and a track depending on the light point. Thus, the user can use the light point as a cursor to control the computer.
When using the pointer to control a projector or a computer, in order to prevent the image which is projected from projection device from affecting the image sensor, the image sensor usually contains a filter, which can filter out the visible light and allow the infrared light to reach the image sensor. Hence, the image sensor can only sense the infrared light and not sense the visible light. Therefore, when controlling the interactive projection system, the image sensor can not be affected by the image projected from projection device, so as to attenuate the incorrect operation of the projection device of the computer.
Before using the interactive projection system, a calibration of position usually needs to be performed to make the screen correctly show the position and the track depending on the light point. Since the image sensor can not sense the visible light, some common interactive projection systems need to use the invisible light points to perform the calibrations of position. Thus, the present calibration of the position of the light point usually needs a user to carry out. That is, the calibration of position generally is performed manually.